The faculty of the Cardiovascular Fluid Mechanics Laboratory at the Georgia Institute of Technology propose the acquisition of new research equipment to allow for state-of-the-art velocity measurement visualization in cardiovascular flow fields. The equipment comprises two major items: (i) a three dimensional, fiber optic, laser Doppler velocimeter (LDV); and (ii) a Silicon Graphics Iris (SGI) 4D/380 GTX Power System Computer. Investigators in the Laboratory are studying the relationship of fluid dynamics phenomena to cardiovascular disease processes, vascular biology and noninvasive disease detection under several currently funded NIH grants; and the ability to quantify and visualize fluid dynamic behavior is essential in order to accomplish their research objectives. The LDV system will allow measurement of three components of flow velocity in models of the cardiovascular system, and the fiber optics allow particular flexibility in the positioning of the interrogated locations. This dual capability allows study of the macroscopic flow field in models with realistic anatomical configurations and also enables the investigation of near-wall flow phenomena so important in understanding the interaction of fluid dynamics with vessel walls. The Silicon Graphics system will be employed for multiple research purposes. Velocity data obtained with the LDV system will be acquired and processed with the computer hardware and software. The system will also be used for computational fluid dynamics applications in which velocity, pressures and species concentrations are computed for cardiovascular geometries and flow conditions. Visualization of either experimental data or computed flow fields is critical to the understanding of flow phenomena and their implications to cardiovascular disease and basic biological phenomena. Additionally, investigators in the Biofluid Dynamics Laboratory have developed new algorithms for identifying and tracking the motion of small particles in flow fields using image processing techniques, thus giving information on fluid-particle and particle-wall interactions. The utility of this new tool is presently restricted by inadequate computer and graphics power in the laboratory. The proposed SGI system will greatly extend the capability and applications of this method. Faculty with appointments in three different academic units will share in the use and maintenance of the equipment. The instruments will thus form a central facility which will be employed in currently sponsored NIH research programs of seven investigators and will be used in the development of new research proposals.